Key West Museum of Art and History at the Custom House

The big red-brick building that towers over Mallory Square is the old U.S. Custom House, and it is the best single place to understand how Key West came to be. Opened in 1891 in the heavy, arched Richardsonian Romanesque style, it housed the customs office, the post office and the federal courts when Key West was one of the busiest ports in the country — and in 1898 it was the site of the naval court of inquiry into the explosion of the USS Maine in Havana harbor, the event that launched the Spanish-American War. The Navy later took it over as a headquarters for Caribbean and Gulf operations, then declared it surplus, and it sat empty for nearly twenty years until the state bought it in 1991 and leased it to the Key West Art and Historical Society, which restored it into an award-winning museum. Today two floors of galleries, with tall windows and pressed-metal detail, cover two centuries of island history, people and art: the wreckers and spongers, the cigar makers who arrived from Cuba, Henry Flagler's railroad to the sea, the writers and painters who found their way here, and the island's folk artists. Exhibitions rotate, so the specific shows change through the year, but the building itself is the constant star. Allow about an hour. It is air-conditioned, uncrowded compared with the square outside, and an excellent way to fill the hour before sunset. The trade-off: it is a reading-and-looking museum without hands-on displays, so younger children may drift, and if you only have time for one museum, choose by theme — this one is the broadest overview of Key West history.

The building tells the story by itself. Its size reflects the wealth of nineteenth-century Key West, when wrecking, sponging, cigars and shipping made the island the largest city in Florida and federal business here mattered. The Maine inquiry connects it to a turning point in American history: the court of inquiry that met here took testimony from survivors of the battleship that blew up in Havana, and the outcry that followed helped push the United States into war with Spain. Through the twentieth century, as Key West's fortunes rose and fell with the Navy, the building followed the same arc, and its decline and rescue mirror the island's own preservation story. The restoration brought back its grand stair and high-ceilinged rooms.

Visiting: the museum opens daily from morning until late afternoon, with last admission half an hour before closing, and tickets are a little cheaper online. The Key West Art and Historical Society also runs Fort East Martello, the Key West Lighthouse and the Tennessee Williams Museum, and its Museum Culture Pass bundles them, which is good value if you plan to visit two or more. Check what is showing before you go; the society regularly mounts exhibitions on Hemingway-era Key West, local artists and island history, and the gallery talks and events listed on its site are worth catching. There is a museum shop with local books and art, and the building's upper-floor windows frame some of the best views over Mallory Square and the harbor.

Fit and pairing: the Custom House sits at 281 Front Street, right beside Mallory Square, so the natural plan is an hour here in the late afternoon, then out onto the square for the sunset celebration. It also pairs well with the Key West Aquarium and the Shipwreck Treasure Museum on the square itself, and with the Mel Fisher Museum a block away. History buffs and art lovers will enjoy it most; first-time visitors who want context for everything else they will see on the island should make it an early stop.